eChapters

Plant diseases are a recurring threat. Everywhere they appear in a certain cycle. Chains of infection (pathogenesis) initiated by primary inoculums comes spontaneously at the end of the harvest season or at host death due to the production of various types of pathogenic reproductive organs/propagules. These propagules must find ways to bridge the gap between harvest times to ensure continuity of infection. Therefore, plant pathogen survival is a critical step in a successful pathogen disease cycle. Pathogen spread is another important phenomenon in plant disease recurrence and epidemiology. Effective spread/diffusion of virulent propagules is critical for initiation of chains of infection and further progression of the disease in time and space.

Definition

The availability of a plant pathogens in given area depends upon its ability to survive not only during its parasitic relations with hosts but also during those seasons in which the hosts are not growing. The latter part of continued existence of plant pathogens in which they remain in dormant condition to overcome the unfavourable condition of non availability of hosts is called “survival”. Pathogens may survive between crop seasons by means of specialized resting structures , by functioning as saprophyte in or on the soil or in diseased plant debris, or by living in some intimate association with living plants or other organism.

The availability of a plant pathogens in given area presupposes its ability to survive not only during its parasitic relations with hosts but also during those seasons in which the hosts are not growing. The latter part of continued existence of plant pathogens in which they remain in dormant condition to overcome the unfavourable condition of non availability of hosts is called “survival”. Pathogens may survive between crop seasons by means of specialized resting structures, by functioning as saprophyte in or on the soil or in diseased plant debris, or by living insome intimate association withlivingplants or otherorganism.

Modes of Survival: The modes of survival of plant pathogens are described below:

1. Parasitic Survival

Organisms, parasitic on perennial plants (fruits, plantation and forest trees) survive in or on their hosts actively or passively depending on the environmental conditions. Certain bacterial pathogens viz, X. campestris pv citri, X. campestris pv jugalandis, X. campestris pv. Pruni and Erwinia amylovora are known to be carried over perennially in holdover cankers or blighted twigs, which may produce bacterial ooze in favourable weather to fresh inoculums. Similarly several fungal plant pathogens like Colletotrichum gloeosporioides (anthracnose of mango), Oidium mangiferae (powdery mildew of mango), Podosphaera leucotricha (powdery mildew of apple), etc survive on infected organs of the plants. Along with cultivated crops, several undesirable plant (weeds, etc) both annual and perennial, grow independently in the nature. Such plants which belong to the same botanical family to which cultivated hosts belong , are known as collateral hosts. Some important examples include the survival of three Puccinia spp. causing wheat rusts in Indian subcontinent . These fungi survive in active sporulating stage on wild species of Triticum, Aegilops, Horedeum and Agropyron repens. Similarly, Rice tungro virus survive actively on Oryza spp., Echinocloa spp. and Leersia hexandra .

Weeds have specific characters which helps them to adapt to any stressful situation and successfully, compete with the crop. They have survival strategies which help them to overcome vagaries of nature like extreme cold, heat, drought, biotic stresses and soil abnormalities. Their most important characteristic is the ability to succeed in any adverse situation even in disturbed soils. The age old war between man and weeds makes it pertinent to understand the characteristics of weeds which make them better competitors in the field.

Abstract

This paper is the synthesis of researches of quaternary on the Chad lake basin, our field investigations, our previous palaeogeographic research underlined by the sédimentological analyses, ¹⁴C radiocarbon and thermoluninescence dating. The objective is to show that after the effects of geological fluctuation, paleoclimatic oscillations, the Chad lake basin experiences since historical times an increasingly drying up due to the combination of geographic factors such as its close position in the Sahara desert, centre of the climate dynamics and human activities. This situation frequently generates recurrent live conditions to which man has to face.

Introduction

Climate change represents a threat not only to the existence of individual species, but also to the genetic diversity hidden within them. The finding promises to complicate assessments of how climate change will affect biodiversity, as well as conservationists’ task in preserving it.

Climate change comes as an additional factor affecting a livestock sector that is already highly dynamic and facing many challenges. Important objectives of AnGR management include ensuring that AnGR are effectively deployed to meet these challenges (i.e. are well matched to the production environments in which they are kept) and that the genetic diversity needed to adapt production systems to future changes is maintained. Climate change is likely to create a number of problems in many areas of animal husbandry (housing, feeding, health care, etc.) and threaten the sustainability of many livestock production systems and their associated AnGR. At the same time, many of the specific challenges associated with climate change (high temperatures, disruptions to feed supplies, disease outbreaks, etc,) as well as the general unpredictability it brings to the future of the livestock sector, highlight the importance of retaining diverse genetic options for the future. The upper critical temperature of dairy cattle is lower than other livestock species (Wathes et al.,1983).

Abstract

Determining the optimum stocking rate for a grazing land is a key decision affecting the profitability and viability of a grazing system. Forage intake and subsequent performance is dependent on forage availability to the livestock on a daily basis.
Fixing stocking rate too low results in wastage of forage and loss in profit and too high results in lowered forage intake and livestock output thus results in diminished profits. Overgrazing occurs when the grazing pres-sure exceeds the carrying capacity of the land and would modify the physical properties of soil and ecosystem. Due to the overuse of the grazing land, vegetation cover declines and thus reduces the soil organic matter content and soil infiltration capacity. On farm field experiments were conducted in three farmer’s fields at dryland tracts of Tirupur district for a period of two years from September, 2009 to March, 2011 with the objective to assess the carrying capacity of silvipastoral farming system. Treatments were five silvipastoral systems viz.,Acacia leucophloea + Cenchrus ciliaris, Acacia leucophloea + Cenchrus ciliaris + Stylosanthes hamata, Acacia leucophloea + Cenchrus setigerus + Stylosanthes hamata, Acacia leucophloea + fodder sorghum + Pillipesara and Acacia leucophloea + Cenchrus setigerus + Stylosanthes hamata & fodder sorghum + Pillipesara. One unit of Mecheri sheep of five ewes (female) and one ram (male) and two buffaloes were maintained in each location. Observations on carrying capacity, annual forage yield, utilization rate, average daily intake and average fodder requirement of sheep and Length of grazing season were made. The experimental results revealed that, among the different silvipastoral systems, rotational grazing of 39 numbers of sheep per ha of silvipasture land with Cenchrus setigerus + Stylosanthes hamata & fodder sorghum + Pillipesara system is found to be the best. This would imply relatively less pressure on land that would indicate sustaining the carrying capacity of grazing land without exerting pressure on natural resources.

India is very rich in biodiversity especially in animal genetic resources and animals have been part and parcel of agricultural heritage. There are about 30 well defined breeds of cattle found in different parts of the country. To name a few are Sahiwal, Red Sindhi, Gir, Kankrej, Deoni, Tharparkar, Hariana, Ongle, Nagori, Amritmahal and Hallikar. The cattle breeds are classified into three types i.e. dairy, dual purpose and draft/drought animals. The number of the animals of majority of indigenous breeds has declined over the years. Further, their number is very low and majority of cattle population (80%) in India is non-descript. The introduction of systematic crossbreeding program of our native cattle with exotic breeds in seventies have further led to the depletion of prized germplasm of all the indigenous breeds under farm and field conditions. However, considering the importance of indigenous cattle, some of the breed improvement programs have been initiated to conserve and multiply these breeds. The associated herd progeny testing program has been going on at NDRI Karnal for the genetic improvement of Sahiwal cattle. All India Coordinated Research Project on Hariana and Ongole cattle has been undertaken at different centres by Project Directorate on Cattle, Meerut. Lately, three more breeds namely Sahiwal, Gir and Kankarej have been included in the indigenous breed improvement program (IBP) and different centres have been identified as germplasm units and data recording units for different breeds under the program.

Sustainability Issues Regarding Major Marine Raw Materials Used in Aquaculture Diets

In 2018, more than 70% of the fish production is from fed aquaculture where f ish meals (FMs) and fish oils (FOs) are the main marine raw materials used in aquaculture diets or fish feed (Hua et al. 2019). They are derived or reduced products from the catch of small, pelagic, low-priced marine fish (forage fish) like Peruvian anchoveta that are rich in protein, micronutrient and lipid and are commonly termed as the ‘feed grade marine fishery’ (Bell and Waagbø, 2008; Bendiksen et al. 2011). The whole fish or any other f ish processing by-products are either cooked and then pressed to produce a liquid which on centrifuging produce the fish oil or are dried and crushed into powder-like material which is called as the fish meal (FAO, 2020). FM has the enough balance and concentration of essential amino acids and FO are rich in n-3 essential fatty acids especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). FM and FO are the main ingredients in aquaculture diets as they are relatively cheap, readily available, accepted and digested by the fish. The highest amount of these ingredients are often used in feeds for the high value aquatic organisms like carnivorous finfish (eg: Dicentrarchus labrax, Rachycendron canadum) (mostly marine), eels, salmonids, trouts, marine shrimps and freshwater crustaceans (see figure 1) etc. (Houlihan et al. 2001; Halver and Hardy, 2002; Miller et al. 2008) which are mainly imported by prosperous countries adding to good seafood trade value. All the intensive aquaculture production systems like recirculatory aquaculture systems, raceway aquaculture systems, aquaponics, cage culture, shrimp ponds etc are the major end users of the marine raw materials.

Abstract

Buffaloes are considered to be the principle milk producing livestock species in India and Surti is one of the well-defined buffalo breeds of India. The study on lactation curve and persistency is very much helpful to know the sustainability of the lactation. The present study is based on daily milk production records for 298 lactations from 130 buffaloes belonging to 15 sires. Lactation curve was prepared through Statistical Packages for Social Sciences programme. Two functions, i.e. gamma function and inverse polynomial functions were fitted to the daily milk yield records. Persistency was calculated through simple analysis in Microsoft Excel 2000 on the weekly records of the milk yield. Gamma function was found to be more effective as compared to inverse polynomial function with higher R2 value for all the four lactations, which indicated that gamma function can be effectively used to establish lactation curve and predict milk yield of animals on any day of lactation. The value of persistency ranged from 97.94% in fourth lactation to 98.56 % in first lactation, indicating Surti buffaloes as fairly persistent in milk production throughout the lactation.

In the study of rural development, there are three frameworks of analysis, viz. neo-classical, Marxian and systems approaches. While the latter two are holistic approaches, the neo-classical framework provides the underpinning of modern microfinance, with its focus on the decision making of individual economic agents towards (short-term) profit or utility maximisation. Neo-classical discussion and policy prescriptions in microfinance are directed towards creating the conditions for the operation of free rural financial markets. Institutional economists have further used the imperfect information paradigm to focus on transaction costs of credit delivery that serve to explain and justify high interest rates charged by village moneylenders (Tankha, 2002).

Introduction

The prosperity of Tamil Nadu depends on the development of rural areas. As per the 2001 Census, Tamil Nadu’s rural population was 36.2 million, amounting to 58% of the total population. Of these 90 percent are earning their livelihood through agriculture and allied activities. The agricultural situation in Tamil Nadu largely depends on the quantum of rainfall received during seasonal rainfall of South West and North East monsoon. North East monsoon which occurs around September to November is more crucial as South West monsoon which will give enormous rainfall to other Indian states is blocked by Western Ghats. So Tamil Nadu is receiving low rainfall and it also comes in three to five heavy showers during October and November. This limits the wet period (good condition for cultivation) to two to five weeks for the whole season. The wet period is further shortened by fast wind and soil type in some area. Thus, the success of the crop is largely determined by one’s capacity to exploit the short wet period. Even though the Tamil Nadu is relatively better position in tapping available ground water resources (92 percent of potential has been tapped), 82 percent of the well is owned by medium and large farmers who is only 10 per cent of total cultivators.

The past development efforts in India center around individual approach and these efforts did not bring about sustained development of people in the respective areas. In view of this, the development of the people could not be harnessed to the fullest potential. Realizing this lacuna, the group based development efforts have come up in a big way across the country in the recent years. The Government, private organizations and also the NGOs are giving due importance for the promotion and establishment of Self Help Groups (SHGs) for addressing all developmental issues. As on today, there are more than 3.37 million SHGs across the country, Tamil Nadu is one of the pioneering states in the formation and promotion of women SHGs and about 4.41 lakh SHGs are functioning in the state. Among the SHGs formed, some of the SHGs are functioning well and sustain for a longer period and others did not come up to the expectation and they did not sustain for longer period. Hence, it was considered opportune time to find out the sustainability level of the SHGs and isolate factors for variation since there was no research back up.
 
Therefore, the study was undertaken to analyse the sustainability of mixed enterprises  related SHGS in Tamil Nadu with an intention to find out the extent of sustainability at different levels.  The study was conducted in Dharmapuri District of Tamil Nadu. Five blocks namely Dharmapuri, Harur, Morappur, Nallampalli, and Pennagaram were selected from the district based on maximum number of SHGs.

Sustainability issues have infused sanity in utilizing interventions without much damage to the environment. The wisdom of the practitioners, who had over generations developed their own eco-friendly practices, is being appreciated. Recent researches have aimed at documenting, rationalizing, and blending the Indigenous Knowledge with the so called Scientific or Western knowledge so as to take care of the sustainability issues. Many researchers have contributed to this pool of knowledge by documenting many of the technologies, crop wise, area wise and operation wise and so on.

Agriculture is the most significant part of economies of all African countries and can therefore contribute towards major priority for eradication of hunger and poverty. It also forms the strong base for rapid industrialization, employment and environmental management.
N. KozanaDiaminiLuma, the Chairperson of the African Union Commission has emphasized that ‘the year 2014 – the year of Agriculture in Africa’ will be used as an opportunity to accelerate the drive for food security. The major thrust for that has to be on ensuring that the farmers make their profession on economic activity that generate well-being for all in a sustainable manner (1, 2). Africa will have a population of 2 billion people by 2050, the majority women and youth. This prediction and the climate change problem summarize the scale of agricultural challenge for them. Currently more than half of all people living in Africa depend on agriculture for all or part of their livelihood. *Based on Key Note address by the author at the First International Agri Business Conference at Mauritius, Africa : 25 – 28 September 2008
EVER GREEN REVOLUTION OR ECO AGRI REVOLUTION FOR AFRICA
Nearly all agree that Africa needs technology for farming comparable to the Green Revolution of Asia. In 2006, two major philanthropic foundations namely Gates Foundations & Rockefeller foundations joined in a joint venture called Alliance for a Green Revolution in Africa (AGRA). They emphasized the importance of introducing African small fodder farmers to modern agricultural science.However, this was rejected strongly by some calling it “naivete” about the causes of hunger and warned that this approach

African agriculture is in crisis, and Africa’s farmland is losing its fertility at an alarming rate. Farmers grow the same crops in the same fields year. They don’t fertilize, and they don’t terrace their fields. When the soil wears out, the clear a new piece of land (wwww.npr.org). N. Kozana Diamini Luma, the Chairperson of the African Union Commission has emphasized that ‘the year 2014 – the year of Agriculture in Africa’ will be used as an opportunity to accelerate the drive for food security. The major thrust for that has to be on ensuring that the farmers make their profession on economic activity that generate wellbeing for all in a sustainable manner (1, 2).

In contrast to the traditional universities, agricultural universities have been entrusted with the Herculean task of technology dissemination at the grass root level such that the package of practices evolved by the agricultural scientists should reach out the end-users, viz. farmers , for adopting in the field, with consequent increment in the farm productivity and farmer’s income. This unique mandate has been assigned to agricultural universities on the pattern of land grant colleges of the United States. Such vision and trust, envisaged by Pandit Jawaharlal Nehru and his devout lieutenants, herald creation of state agricultural universities (SAUs) in the early 1960s. The key role played by SAUs in the first green revolution and agricultural human resources development have been regarded as the milestones in the history of India post-independence, that made the country self-sufficient in food production and, in turn, to self reliance in milk, vegetables, fruits and inland fish production. Today, India has set fourth into commanding position as a global economic power, with primary and secondary sectors, viz. agriculture and industry, contributing modestly. At the current pace of the growth rate, I would not hesitate to predict that by the year 2020, we will accomplish the top lines both in terms of productivity and sustainability, by transforming hitherto deemed liability of population into a formidable asset of human resource capital.
Hunger-free World
Agriculture is a vital development tool for achieving the Millennium Development Goals that call for halving by 2015 the number of people, suffering from extreme poverty and hunger. We also note that more than 50% of the people in the world are small and resource-poor farmers and another 20% rural land less. The challenge is to transform this

In contrast to the traditional universities, agricultural universities have been entrusted with the Herculean task of technology dissemination at the grass root level such that the package of practices evolved by the agricultural scientists should reach out the end-users, viz. farmers , for adopting in the field, with consequent increment in the farm productivity and farmer’s income.

This unique mandate has been assigned to agricultural universities on the pattern of land grant colleges of the United States. Such vision and trust, envisaged by Pandit Jawaharlal Nehru and his devout lieutenants, herald creation of state agricultural universities (SAUs) in the early 1960s. The key role played by SAUs in the first green revolution and agricultural human resources development have been regarded as the milestones in the history of India post-independence, that made the country self-sufficient in food production and, in turn, to self reliance in milk, vegetables, fruits and inland fish production.

1. Introduction

The agriculture sector in Asia and the Pacific plays a vital role in the rural economy, making significant contributions to both GDP and employment. This sector serves as a cornerstone for food production, economic growth and poverty reduction in the region. Understanding the importance of farming in the region’s rural economy, as well as the need for viable farming systems particularly for smallholder farms, is essential for sustainable development.

Importance of Farming in the Rural Economy

Farming has a substantial impact on the rural economy of Asia and the Pacific. It serves as a primary source of income and livelihood for rural populations, contributing significantly to the region’s Gross Domestic Product (GDP). The agricultural sector encompasses a wide range of activities, including crop production, livestock farming, fisheries, and forestry, providing diverse opportunities for economic development.

According to the Food and Agriculture Organization (FAO), farming accounts for 29 percent of the region’s GDP (FAO, 2021). This demonstrates the significant economic value that agriculture brings to the region, making it a crucial sector for sustainable development. The revenue generated from agricultural activities supports not only farmers but also other stakeholders in the value chain, including agro-industries, distributors, and exporters.

Conservation Agriculture

The agronomic measures for water conservation helps to control the evapotranspiration loss from soil and plant surface, reduces the splash effect of raindrops, checks topsoil erosion and runoff losses, permits a better intake of rainwater by improving the better soil physical environment and thereby conserves higher soil moisture for better plant growth and yield.

1. Mulching : It protects the top soil from erosion loss by controlling runoff, facilitates rainwater absorption by soil, increases the consumptive use of water by crops and hence the water use efficiency, regulates the hydrothermal regime of soil, reduces the evaporation component of the evapotranspiration, prevents soil crusting and plant nutritional losses and keep down the weed infestation. Dry soil mulch as created by stirring the soil surface with the inter-culturing implements helps to minimize evaporation loss from soil surface. Use of cover mulches like black polythene sheets or organic residues or crop stubbles on soil surface will act as barrier to reduce the evaporation losses. Post-rainy season crops (rabi crops) which live primarily on soil stored moisture derive more benefit from mulching.
2. Anti-evaporants : These are used to reduce the evaporation from the soil surface. Straw, sawdust, paddy husk, wood bark etc are used to arrest the evaporation from soil surface. Hexadecanol, a long-chain alcohol, is also used to retard the evaporation from soil surface. This chemical is resistant to microbial activity and degradation and remains active in the soil for more than a year. The main limitation in soil surface mulching is high cost involvement.